'\" te
.\"  Copyright 2014 Garrett D'Amore <garrett@damore.org>
.\"  Copyright (c) 2006, Sun Microsystems, Inc.,  All Rights Reserved
.\" The contents of this file are subject to the terms of the Common Development and Distribution License (the "License").  You may not use this file except in compliance with the License.
.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing.  See the License for the specific language governing permissions and limitations under the License.
.\" When distributing Covered Code, include this CDDL HEADER in each file and include the License file at usr/src/OPENSOLARIS.LICENSE.  If applicable, add the following below this CDDL HEADER, with the fields enclosed by brackets "[]" replaced with your own identifying information: Portions Copyright [yyyy] [name of copyright owner]
.TH SCSI_INIT_PKT 9F "May 24, 2014"
.SH NAME
scsi_init_pkt \- prepare a complete SCSI packet
.SH SYNOPSIS
.nf
#include <sys/scsi/scsi.h>



\fBstruct scsi_pkt *\fR\fBscsi_init_pkt\fR(\fBstruct scsi_address *\fR\fIap\fR,
     \fBstruct scsi_pkt *\fR\fIpktp\fR, \fBstruct buf *\fR\fIbp\fR, \fBint\fR \fIcmdlen\fR, \fBint\fR \fIstatuslen\fR,
     \fBint\fR \fIprivatelen\fR, \fBint\fR \fIflags\fR, \fBint\fR \fB(*\fRcallback\fB)(caddr_t)\fR, \fBcaddr_t\fR \fIarg\fR);
.fi

.SH INTERFACE LEVEL
illumos DDI specific (illumos DDI).
.SH PARAMETERS
.ne 2
.na
\fB\fIap\fR\fR
.ad
.sp .6
.RS 4n
Pointer to a \fBscsi_address\fR(9S) structure.
.RE

.sp
.ne 2
.na
\fB\fIpktp\fR\fR
.ad
.sp .6
.RS 4n
A pointer to a \fBscsi_pkt\fR(9S) structure.
.RE

.sp
.ne 2
.na
\fB\fIbp\fR\fR
.ad
.sp .6
.RS 4n
Pointer to a \fBbuf\fR(9S) structure.
.RE

.sp
.ne 2
.na
\fB\fIcmdlen\fR\fR
.ad
.sp .6
.RS 4n
The required length for the \fBSCSI \fRcommand descriptor block (\fBCDB\fR) in
bytes.
.RE

.sp
.ne 2
.na
\fB\fIstatuslen\fR\fR
.ad
.sp .6
.RS 4n
The required length for the \fBSCSI \fRstatus completion block (\fBSCB\fR) in
bytes. Valid values are:
.sp
.ne 2
.na
\fB\fB0\fR\fR
.ad
.sp .6
.RS 4n
No status back.
.RE

.sp
.ne 2
.na
\fB\fB1\fR\fR
.ad
.sp .6
.RS 4n
Return SCSI status byte.
.RE

.sp
.ne 2
.na
\fB\fBsizeof(scsi_arq_status)\fR\fR
.ad
.sp .6
.RS 4n
Return status information in a \fBscsi_arq_status\fR structure. This will
include up to 20 bytes of sense data. Please refer to \fBscsi_arq_status\fR(9S)
for more information.
.sp
For extra sense packets (\fBPKT_XARQ\fR flag asserted), set \fIstatuslen\fR to
be a greater number like, (\fIN\fR + \fBsizeof(struct scsi_arq_status)\fR)
where \fIN\fR is the number of extra bytes beyond the default 20. For example,
\fIN\fR=1 requests 21 bytes of sense, \fIN\fR=235 asks for 255 bytes.
.RE

.RE

.sp
.ne 2
.na
\fB\fIprivatelen\fR\fR
.ad
.sp .6
.RS 4n
The required length for the \fIpkt_private\fR area.
.RE

.sp
.ne 2
.na
\fB\fIflags\fR\fR
.ad
.sp .6
.RS 4n
Flags modifier.
.RE

.sp
.ne 2
.na
\fB\fIcallback\fR\fR
.ad
.sp .6
.RS 4n
A pointer to a callback function, \fBNULL_FUNC\fR, or \fBSLEEP_FUNC\fR.
.RE

.sp
.ne 2
.na
\fB\fIarg\fR\fR
.ad
.sp .6
.RS 4n
The \fIcallback\fR function argument.
.RE

.SH DESCRIPTION
Target drivers use \fBscsi_init_pkt()\fR to request the transport layer to
allocate and initialize a packet for a \fBSCSI\fR command which possibly
includes a data transfer. If \fIpktp\fR is \fINULL,\fR a new \fBscsi_pkt\fR(9S)
is allocated using the \fBHBA\fR driver's packet allocator. The \fIbp\fR is a
pointer to a \fBbuf\fR(9S) structure. If \fIbp\fR is non-\fINULL\fR and
contains a valid byte count, the \fBbuf\fR(9S) structure is also set up for
\fBDMA \fRtransfer using the \fBHBA\fR driver \fBDMA\fR resources allocator.
When \fIbp\fR is allocated by \fBscsi_alloc_consistent_buf\fR(9F), the
\fBPKT_CONSISTENT\fR bit must be set in the \fIflags\fR argument to ensure
proper operation. If \fIprivatelen\fR is non-zero then additional space is
allocated for the \fIpkt_private\fR area of the \fBscsi_pkt\fR(9S). On return
\fIpkt_private\fR points to this additional space. Otherwise \fIpkt_private\fR
is a pointer that is typically used to store the \fIbp\fR during execution of
the command. In this case \fIpkt_private\fR is \fINULL\fR on return.
.sp
.LP
The \fIflags\fR argument is a set of bit flags. Possible bits include:
.sp
.ne 2
.na
\fB\fBPKT_CONSISTENT\fR\fR
.ad
.sp .6
.RS 4n
This must be set if the \fBDMA\fR buffer was allocated using
\fBscsi_alloc_consistent_buf\fR(9F). In this case, the \fBHBA\fR driver will
guarantee that the data transfer is properly synchronized before performing the
target driver's command completion callback.
.RE

.sp
.ne 2
.na
\fB\fBPKT_DMA_PARTIAL\fR\fR
.ad
.sp .6
.RS 4n
This may be set if the driver can accept a partial \fBDMA\fR mapping. If set,
\fBscsi_init_pkt()\fR will allocate \fBDMA\fR resources with the
\fBDDI_DMA_PARTIAL\fR bit set in the DMA flags.
The \fBpkt_resid\fR field of the
\fBscsi_pkt\fR(9S) structure may be returned with a non-zero value, which
indicates the number of bytes for which \fBscsi_init_pkt()\fR was unable to
allocate DMA resources. In this case, a subsequent call to
\fBscsi_init_pkt()\fR may be made for the same \fIpktp\fR and \fIbp\fR to
adjust the DMA resources to the next portion of the transfer. This sequence
should be repeated until the \fBpkt_resid\fR field is returned with a zero
value, which indicates that with transport of this final portion the entire
original request will have been satisfied.
.RE

.sp
.ne 2
.na
\fB\fBPKT_XARQ\fR\fR
.ad
.sp .6
.RS 4n
Setting this flag requests that the \fBHBA\fR return  extra sense data for this
\fBscsi_pkt\fR(9S). The default  auto request sense mechanism returns up to  20
bytes. More than 20 bytes of sense data can be requested by setting this flag
and setting the \fIstatuslen\fR correctly. Set the \fIstatuslen\fR to be the
\fBsizeof(struct scsi_arq_status)\fR plus the number of sense bytes needed
beyond 20. For example, set statuslen to be \fB(sizeof(struct scsi_arq_status)
+ 5)\fR for 25 bytes of sense.
.RE

.sp
.LP
When calling \fBscsi_init_pkt()\fR to move already-allocated \fBDMA\fR
resources, the \fIcmdlen\fR, \fIstatuslen\fR, and \fIprivatelen\fR fields are
ignored.
.sp
.LP
The last argument \fIarg\fR is supplied to the \fIcallback\fR function when it
is invoked.
.sp
.LP
\fIcallback\fR indicates what the allocator routines should do when resources
are not available:
.sp
.ne 2
.na
\fB\fBNULL_FUNC\fR\fR
.ad
.RS 16n
Do not wait for resources. Return a \fINULL\fR pointer.
.RE

.sp
.ne 2
.na
\fB\fBSLEEP_FUNC\fR\fR
.ad
.RS 16n
Wait indefinitely for resources.
.RE

.sp
.ne 2
.na
\fBOther Values\fR
.ad
.RS 16n
\fIcallback\fR points to a function which is called when resources may have
become available. \fIcallback\fR must return either \fB0\fR (indicating that it
attempted to allocate resources but again failed to do so), in which case it is
put back on a list to be called again later, or \fB1\fR indicating either
success in allocating resources or indicating that it no longer cares for a
retry.
.RE

.sp
.LP
When allocating \fBDMA\fR resources, \fBscsi_init_pkt()\fR returns the
\fBscsi_pkt\fR field \fBpkt_resid\fR as the number of residual bytes for which
the system was unable to allocate \fBDMA\fR resources.  A \fBpkt_resid\fR of
\fB0\fR means that all necessary \fBDMA\fR resources were allocated.
.SH RETURN VALUES
The \fBscsi_init_pkt()\fR function returns \fINULL\fR if the packet or
\fBDMA\fR resources could not be allocated. Otherwise, it returns a pointer to
an initialized \fBscsi_pkt\fR(9S). If \fIpktp\fR was not \fINULL\fR the return
value will be \fIpktp\fR on successful initialization of the packet.
.SH CONTEXT
If \fIcallback\fR is \fBSLEEP_FUNC\fR, then this routine can be called only
from user-level code. Otherwise, it can be called from user, interrupt, or
kernel context. The \fIcallback\fR function may not block or call routines that
block.
.SH EXAMPLES
\fBExample 1 \fRAllocating a Packet Without \fBDMA\fR Resources Attached
.sp
.LP
To allocate a packet without \fBDMA\fR resources attached, use:

.sp
.in +2
.nf
pkt = scsi_init_pkt(&devp->sd_address, NULL, NULL, CDB_GROUP1,
        1, sizeof (struct my_pkt_private *), 0,
        sd_runout, sd_unit);
.fi
.in -2

.LP
\fBExample 2 \fRAllocating a Packet With \fBDMA\fR Resources Attached
.sp
.LP
To allocate a packet with \fBDMA\fR resources attached use:

.sp
.in +2
.nf
pkt = scsi_init_pkt(&devp->sd_address, NULL, bp, CDB_GROUP1,
        sizeof(struct scsi_arq_status), 0, 0, NULL_FUNC, NULL);
.fi
.in -2

.LP
\fBExample 3 \fRAttaching \fBDMA\fR Resources to a Preallocated Packet
.sp
.LP
To attach \fBDMA\fR resources to a preallocated packet, use:

.sp
.in +2
.nf
pkt = scsi_init_pkt(&devp->sd_address, old_pkt, bp, 0,
        0, 0, 0, sd_runout, (caddr_t) sd_unit);
.fi
.in -2

.LP
\fBExample 4 \fRAllocating a Packet with Consistent \fBDMA\fR Resources
Attached
.sp
.LP
Since the packet is already allocated, the \fIcmdlen\fR, \fIstatuslen\fR and
\fIprivatelen\fR are \fB0\fR. To allocate a packet with consistent \fBDMA\fR
resources attached, use:

.sp
.in +2
.nf
bp = scsi_alloc_consistent_buf(&devp->sd_address, NULL,
	       SENSE_LENGTH, B_READ, SLEEP_FUNC, NULL);
	pkt = scsi_init_pkt(&devp->sd_address, NULL, bp, CDB_GROUP0,
        sizeof(struct scsi_arq_status), sizeof (struct my_pkt_private *),
        PKT_CONSISTENT, SLEEP_FUNC, NULL);
.fi
.in -2

.LP
\fBExample 5 \fRAllocating a Packet with Partial \fBDMA\fR Resources Attached
.sp
.LP
To allocate a packet with partial \fBDMA\fR resources attached, use:

.sp
.in +2
.nf
my_pkt = scsi_init_pkt(&devp->sd_address, NULL, bp, CDB_GROUP0,
          1, sizeof (struct buf *), PKT_DMA_PARTIAL,
          SLEEP_FUNC, NULL);
.fi
.in -2

.SH SEE ALSO
.BR scsi_alloc_consistent_buf (9F),
.BR scsi_destroy_pkt (9F),
.BR scsi_dmaget (9F),
.BR scsi_pktalloc (9F),
.BR buf (9S),
.BR scsi_address (9S),
.BR scsi_pkt (9S)
.sp
.LP
\fIWriting Device Drivers\fR
.SH NOTES
If a \fBDMA\fR allocation request fails with \fBDDI_DMA_NOMAPPING\fR, the
\fBB_ERROR\fR flag will be set in \fIbp\fR, and the \fBb_error\fR field will be
set to \fBEFAULT\fR.
.sp
.LP
If a \fBDMA\fR allocation request fails with \fBDDI_DMA_TOOBIG\fR, the
\fBB_ERROR\fR flag will be set in \fIbp\fR, and the \fBb_error\fR field will be
set to \fBEINVAL\fR.
